The injection of energy into a medium at a relatively large scale, such as occurs when a body is propelled in a fluid medium, develops turbulence in the medium. While turbulence in a fluid medium has the connotation of chaos in which all possible degrees of freedom are excited, it is now generally accepted that coherent patterns exist in the turbulence.
A fundamental property of developed turbulence is that, although most of the energy of turbulent motion is associated with large scales, the dissipation of energy as a consequence of the turbulent motion occurs at small scales comparable to the Kolmogoroff length scale. Such dissipation is manifested by the conversion of molecular movement into heat, and this viscous dissipation takes place mainly in the boundary layer in a fluid medium which exists between a body and the fluid, or between, for example, two fluids of different densities.
Between the large scales where turbulent motion occurs, and the small scales where dissipation of energy occurs, lie intermediate scales often referred to as the inertial range. Energy is transmitted from the non-dissipative large scales to the dissipative small scales through the inertial range scales which thus serve as an energy transmission bridge.
The dissipation of energy due to turbulence, e.g., turbulence created by relative movement between a body and a medium is manifested in different ways. In the case of pipeline transportation of fluid, the dissipation is evidenced by downstream pressure loss; in the case of aircraft flight, or underwater submarine movement, the dissipation is evidenced by increased drag. Flame propagation, and heat transfer associated with turbine blades, as well as often violent, geophysical phenomena such as tornadoes, may constitute additional modalities in which energy injected at relatively large scales, is dissipated due to turbulent flow at small scales.
The usual approach to controlling turbulence and reducing frictional losses in fluid flow is concentrated on improving the finish of surfaces in contact with a fluid. Limits are soon reached, however, on the extent to which surface finish can suppress incipient turbulence. In pipeline transportation of liquids, suppression of turbulence is conventionally achieved by releasing a polymer or surfactant into the liquid boundary layer. The presence of the polymer is believed to modify the boundary layer of flow adjacent to the inner surface of the conduit carrying the liquid, and as a consequence, the momentum of flux is reduced which, in turn, reduces frictional losses. This approach to the suppression of turbulence is appropriate, however, only in cases where a suitable polymer is compatible with the liquid being transported. Moreover, this approach is applicable to only a limited number of flow situations, and its application is furthermore complicated by rapid fatigue of the added substances.
It is therefore an object of the present invention to provide a method for controlling turbulence that is of general application to many modalities.